The present invention pertains to illuminated covers for electronic devices such as cellular telephones. More particularly, the present invention pertains to decorative illuminated covers. The present invention also pertains to an electronic device having an illuminated cover, which might be a decorative illuminated cover. Additionally, the present invention pertains to a method of forming a device cover, including a decorative illuminated cover.
Portable electronic devices, such as cellular telephones, are becoming widely used. Many people desire to have a unique appearing portable electronic device, particular a cellular telephone, not only for its attractiveness, but also to enable them to identify their own phone or other device from devices belonging to other people.
People often have a cellular telephone when in locations in which the ringing of the telephone is undesirable. In such situations, the ringer of the telephone can be shut-off. However, if a call is placed to the telephone while the ringer is off, the user does not know about the call unless there is some other way to indicate its arrival. While some cellular telephones retain a visual indication of unanswered calls, indicating the calling number, the user of such a phone is unlikely to learn of the call until he or she happens to activate the phone next. This may be a considerable time after the call was placed. If the call related to time sensitive information, the user may lose the benefit of the information because he or she did not notice the call soon enough. While a number of light emitting diodes can be incorporated within the cover of a device such as a cellular telephone, so as to be illuminated in response to the ringing current of the telephone, because of power requirements it is impractical to provide a significant illuminated decorative pattern of light emitting diodes.
An electroluminescent foil can be utilized to provide a lighted pattern on a electronic device such as a cellular telephone. However, electroluminescent foils require high ac voltage, in the range of from about 20 volts to about 240 volts at from about 50 Hz to about 300 Hz. Consequently, the electroluminescent foil has to be insulated from the person utilizing the electronic device. Satisfactory insulation can be provided by laminating an electrically insulating foil onto the outer surface of the electroluminescent foil. The combined foils then must be adhered to a support base shaped to provide the desired cover for the electronic device. Such a support base can be formed by placing the combined foils in a mold and injecting plastic or other suitable material. By way of examples, U.S. Pat. Nos. 3,298,558, 4,330,578, 4,495,125, 4,994,224, 5,989,480, and 6,117,384, the disclosures of which are incorporated herein by reference, show techniques for molding plastic articles with decorative patterns.
The support base must have openings through it for passage of control keys of the portable electronic device. Thus, openings must be provided through the electrically insulating foil and the electroluminescent foil. Many electroluminescent foils are fragile and tear easily. Thus, punching an opening in such a foil can cause irreparable damage. Consequently, it is desirable to form the openings during formation of the electroluminescent foil, for example by a printing process. Alternatively, openings might be formed in the electroluminescent foil, for example by punching, before the electroluminescent foil is laminated on the electrically insulating foil, so that any torn or otherwise damaged electroluminescent foil can be discarded or repaired before it is laminated on the electrically insulating foil, avoiding wasting of the electrically insulating foil.
If openings are formed in the electrically insulating foil and the electroluminescent foil before the foils are laminated, the foils must be accurately positioned to assure that the openings through the two foils are aligned. This can be extremely difficult to achieve.
It is necessary for the electroluminescent foil to be connected to a power source. Japanese Patent Publication 10-134960 dated May 22, 1998 shows a molded electroluminescent device having a flexible lead for connection to a power source. However, it is difficult to provide a flexible lead for such connection when the combined foils are adhered to the rigid support base by molding. Frequently, the flexible lead is damaged or destroyed during the molding process, resulting in considerable waste.
To overcome limitations in the prior art described above, and to overcome other limitations that may be apparent upon reading the present specification, the present invention is directed to a device cover and a covered electronic device such as a cellular telephone. In addition, the present invention is directed to a method of forming a device cover for an electronic device. A device cover in accordance with the present invention has a predetermined shape and includes a thin, rigid support base shaped in accordance with the predetermined shape. An electroluminescent foil overlies a first surface of the support base. An electrically insulating foil overlies the electroluminescent foil. If desired, a graphic can be positioned between the electrically insulating foil and the electroluminescent foil. Further, if desired, a thermally insulating foil can be positioned between the support base and the electroluminescent foil to protect the graphic from excessive heat during manufacture of the illuminated cover. However, if no graphic is included, then the thermally insulating foil can be omitted. Likewise, if the graphic would not be damaged by the heat, the thermally insulating foil can be omitted. The support base, the thermally insulating foil, the electroluminescent foil and the electrically insulating foil have a first opening therethrough for insertion of a control key of a device to be covered by the decorative cover. The support base and the thermally insulating foil have a second opening therethrough for insertion of an electrical connector to connect the electroluminescent foil to an electrical power source so as to provide power to the electroluminescent foil. A ridge is formed around the first opening through the electrically insulating foil. The opening through the electroluminescent foil has a diameter enabling the electroluminescent foil opening to surround the electrically insulating foil ridge, accurately positioning the electroluminescent foil on the electrically insulating foil.
A covered electronic device in accordance with the present invention further includes a printed circuit board having a plurality of electronic components mounted on it which are electrically interconnected to form an electronic unit, such as a cellular telephone. The electrical components include a control key for the electronic unit, with the control key extending through the first opening in the decorative cover. The covered electronic device additionally includes a connector extending into the second opening of the decorative cover to connect the electroluminescent foil to circuitry on the printed circuit board so as to provide electrical power to the electroluminescent foil. A second cover member or base cooperates with the support base to enclose the printed circuit board and electronic components, providing a covered electronic device.
In accordance with a preferred embodiment of the present invention, the method of forming a device cover having a predetermined shape includes forming a preliminary cover member by attaching a first surface of an electroluminescent foil to a first surface of an electrically insulating foil, the electrically insulating foil having the predetermined shape and having a first opening therethrough, the electroluminescent foil having an opening therethrough corresponding with the first opening through the electrically insulating foil; placing the preliminary cover member in a mold of the predetermined shape, the mold having bosses corresponding with the first opening and with a second opening; and injecting plastic into the mold and into contact with the preliminary cover member to form the decorative cover, the bosses providing openings through the plastic corresponding with the first and second openings.
The method further may include, before forming the preliminary cover member, preforming the electrically insulating foil to the predetermined shape and forming the first opening through the electrically insulating foil. In a particularly preferred embodiment, the preforming includes forming a ridge around the first opening through the electrically insulating foil, and the electroluminescent foil is attached to the electrically insulating foil with the electroluminescent foil opening surrounding the ridge on the electrically insulating foil to position the electroluminescent foil on the electrically insulating foil. The method may also include forming the opening through the electroluminescent foil. Additionally, the method may include providing a graphic between the electrically insulating foil and the electroluminescent foil, and if desired attaching a thermally insulating foil beneath the electroluminescent foil.